I am searching for the adverbial form of "undefeatable" or a suitable synonym

I am translating a text, and I have a sentence that structurally translates into:

"The noble ideal they have in their sights will enter even the darkest souls and convert undefeatably into a charitable reality like every scientific truth"

I do not believe that "undefeatably" is a valid word. Neither is "unconquerably" or "unbeatably"?

I could use "inevitably" but that is not quite the same. The text is about war and peace - not the book, but the concepts - so, a word that relates to defeat in battle would be appropriate.

Solution 1:

Try inexorably, the adverb form of inexorable, which Merriam-Webster defines as:

not to be persuaded, moved, or stopped : RELENTLESS
inexorable progress

Solution 2:

You could also try:

invincibly = in a way that is impossible to defeat or prevent from doing what is intended

Cambridge dictionary

although I suggest moving away from the battlefield and using:

unquestionably = in a way that is obvious and impossible to doubt

Cambridge dictionary

Solution 3:

How about

invincibly

as in

he kicked the football invincibly.

Here, invincibly modifies kicked and so is an adverb.